1. Technical Field
The present invention relates to a linear guide device and a rolling element accommodating belt for the linear guide device.
2. Related Art
A linear guide device having a plurality of rows of infinite circulating passages includes: as shown in FIG. 29, a guide rail 12; a slider 16 arranged being capable of moving relatively with this guide rail 12; and a plurality of rolling elements 46 (in this example, balls) which roll between the guide rail 12 and the slider 16 under a load. The guide rail 12 has a rolling element guide face 14 on which the rolling elements 46 roll. The slider 16 includes: a slider body 17; and a pair of lid members (end caps) 22 attached to both end portions of the slider body 17 in the moving direction.
For example, as shown in FIG. 30, the slider body 17 includes a load rolling element guide face 18 which is opposed to the rolling element guide face 14 of the guide rail 12. The load rolling element guide face 18 and the rolling element guide face 14 form a rolling element track passage 26 that is a region for giving a load to the rolling elements. The slider body 17 also includes a rolling element return passage 20 in which the rolling elements roll under no load. Further, in the pair of lid members 22, the direction change passages 24 are formed which respectively continue to both end portions of the rolling element track passage 26 and the rolling element return passage 20.
A plurality of rows of the infinite circulating passages 28 are composed of the rolling element track passage 26, the pair of the direction change passage 24 and the rolling element return passage 20. When a plurality of the rolling elements 46 roll in each infinite circulating passage 28, the slider 16 can be relatively moved in the guide rail 12.
In the linear guide device, when the slider is moved relatively with the guide rail, the rolling elements move while they are rolling in the same direction. Therefore, the adjoining rolling elements are rubbed with each other. Accordingly, it is impossible for the rolling elements to roll smoothly. Therefore, an intensity of noise is increased and the rolling elements are early abraded.
In order to solve the above problems, a rolling element accommodating belt is proposed in which the generation of noise is suppressed and in order to smoothly operate the linear guide device, the rolling elements are aligned in the infinite circulating passage so as to compose a rolling element row. (Concerning this technique, refer to Japanese Patent No. 2607993 (Patent Document 1), Japanese Patent No. 3243415 (Patent Document 2), Japanese Patent No. 3447849 (Patent Document 3), Japanese Patent No. 3299450 (Patent Document 4), JP-A-11-247854 (Patent Document 5), Japanese Patent No. 3263005 (Patent Document 6), and JP-A-10-318257 (Patent Document 7))
For example, as shown in FIG. 31, according to the technique described in Patent Document 1, the rolling element accommodating belt 150 includes a spacer member 151 having concave portions on both side faces. This spacer member 151 is provided between the adjoining rolling elements 46 in the infinite circulating passages. Both sides of the adjoining spacer members 151 in the width direction of the infinite circulating passage are connected to each other by a connecting member 152. A portion in which the rolling element 46 is accommodated, which will be referred to as a rolling element accommodating section-hereinafter, is formed by the space member 151 and the connecting member 152 so that the accommodated rolling element 46 can be restrained in all directions and prevented from coming off from the rolling element accommodating section. Due to the above structure, it becomes possible to prevent the rolling elements from being rubbed and competed with each other. Accordingly, the circulating property of the rolling elements can be improved.
Further, for example, as shown in FIG. 30, according to Patent Document 2, the rolling element accommodating belt 62 includes: a spacer member 51; and a connecting member 52. The spacer member 51 has a pair of rolling element contact faces 54a, 54b slidably coming into contact with the outer circumference of the rolling element. The connecting member 52 is a belt-shaped member made of flexible thin material. This connecting member 52 connects the adjoining spacer members to each other. The rolling element 46 is interposed between the adjoining spacer members 51 so that the rolling element 46 can be restrained.
When the rolling elements 46 are accommodated in the rolling element accommodating section formed by the spacer member 51 and the connecting member 52, the rolling element row 62 is composed, and this rolling element row 62 is circulated in the infinite circulating passage 28. Due to the foregoing, it is possible to suppress the rolling elements 46 from being rubbed and competed with each other. Therefore, the circulating property of the rolling elements 46 can be improved. In this case, this rolling element accommodating belt 50 is formed being provided with both end portions, and a gap is formed between both end portions 59 (top and tail) of the rolling element accommodating belt 50, that is, both end portions 59 of the rolling element accommodating belt 50 are not connected to each other. According to this rolling element accommodating belt, it is possible to omit a connecting work in which both end portions of the rolling element accommodating belt are connected to each other so as to form an endless rolling element accommodating belt. Further, it is easy to automatize the assembling process.
However, according to the technique described in Patent Document 1, the rolling element accommodating sections are respectively formed so that all the accommodated rolling elements can be prevented from coming off in all directions of the rolling element accommodating sections. That is, the size of the opening of each rolling element accommodating section is smaller than the outside dimension of the rolling element. Therefore, in order to assemble the rolling element into the rolling element accommodating section from the outside, it is necessary to push each rolling element into each rolling element accommodating section. This assembling work takes time and labor.
In the technique disclosed in Patent Document 1, it is disclosed that at the time of forming the rolling element accommodating belt, each rolling element is accommodated in each rolling element accommodating section by means of insertion forming. Therefore, the process, in which each rolling element is incorporated into each rolling element accommodating section, is not needed. However, in the case where each rolling element is accommodated in each rolling element accommodating section by means of insertion forming at the time of forming the rolling element accommodating belt, the following problems may be encountered. As described in Patent Document 3, in order to give a rotating property to the rolling element (ball), it is takes a very long period of time, and further it is difficult to give a smooth rotating property to the rolling element (ball). In some cases, it is impossible to give a rotating property to the rolling element (ball) according to the type of resin. Further, in order to form an appropriate clearance between the rolling element (ball) and the rolling element accommodating belt, a special process such as a process of sucking water or absorbing oil is needed.
On the other hand, according to the technique described in Patent Document 4, in the rolling element accommodating section, all the accommodated rolling elements can pass through in the direction of both sides of the rolling element accommodating belt. That is, this rolling element accommodating section is formed in the azimuth so that the rolling element can be allowed to come off from the rolling element accommodating section. In this case, in the rolling element accommodating belt, the connecting members are guided by the groove-shaped guide portions formed in the slider on both side in the width direction of the infinite circulating passage. However, according to the technique described in Patent Document 4, all the accommodated rolling elements are accommodated being allowed so that they can come off from the rolling element accommodating section. Accordingly, the rolling element accommodating belt and the rolling elements are moved in the infinite circulating passage independently from each other in the directions of both sides of the rolling element accommodating belt. Consequently, the connecting member of the rolling element accommodating belt is strongly rubbed with the guide section, which might damage the connecting member.
Further, the linear guide device described in Patent Document 1 is composed in such a manner that the spacer members 151 of the rolling element accommodating belt 150 completely hold the rolling elements 46. Therefore, when the connecting member 152 of the rolling element accommodating belt 150 is elastically deformed into an arcuate shape in the direction change passage 24 formed in the lid member (end cap) 22, the spacer members 151 of the rolling element accommodating belt 150 and the rolling elements 46 interfere with each other on the inner circumferential side of the direction change passage 24. Therefore, an excessively strong tensile force is repeatedly given to the connecting member 152 of the rolling element accommodating belt 150. Accordingly, there is a possibility that the connecting member 152 of the rolling element accommodating belt 150 is broken.
In the linear guide device described in Patent Document 5, clearance is made between the rolling element passing in the direction change passage and the end portion on the outer circumferential side of the spacer member. However, in this case, the rolling element rolls in the direction change passage while the spacer member and the rolling element are pushing to each other, that is, while the connecting member is being given a force. Accordingly, in the same manner as that of the case described in Patent Document 1, there is a possibility that the connecting member of the rolling element accommodating belt is broken.
When the above linear guide device is manufactured, the rolling element row is incorporated into each infinite circulating passage by the procedure shown in FIGS. 32(a) to 32(f).
Specifically, the procedure is executed as follows. First of all, as shown in FIGS. 32(a) and 32(b), one of the lid members (end caps) 22 is removed from the slider 16. From the thus opened portion, the rolling element row 62 is inserted into the infinite circulating passage 28. The rolling element row 62 is inserted into the infinite circulating passage 28 until the state shown in FIG. 32(c) can be obtained. In the same manner, as shown in FIG. 32(d), the rolling element row 62 is successively assembled into each infinite circulating passage 28. As shown in FIG. 32(e), after the rolling element rows 62 have been assembled into all infinite circulating passages 28, the lid member 22, which was removed before, is attached to the slider body 17. Finally, as shown in FIG. 32(f), the slider 16, into which the rolling element rows 62 have been assembled, is attached to the guide rail 12.
However, according to this method of manufacturing a linear guide device, when the rolling element row 62 is assembled into each infinite circulating passage 28, as shown in FIGS. 32(d) and 32(e), the end portions 59 of all the rolling element rows are located at the opening portions of the infinite circulating passages 28. Therefore, under the condition that the lid member 22 is attached to the slider body 17 and the opening portions of the infinite circulating passages 28 are closed, positions of the end portions 59 of all the rolling element row 62 are left being aligned.
For example, as described in Patent Document 6, existence of the end portions of the rolling element accommodating belt, which is formed being provided with end portions, can be a cause of obstructing the smooth operation of the linear guide device. That is, since the rolling element accommodating belt, which is bent in the direction change passage, tends to return to a linear shape, the end portion of the rolling element accommodating belt is abraded with the inner wall of the infinite circulating passage, and the circulating resistance is increased. Further, since the rolling element at the end portion of the rolling element accommodating belt proceeds into a region, in which a load is given to the rolling element, without being drawn by the proceeding rolling element, when the rolling element is moved from the no-load region into the load region, a high circulating resistance is generated. In this connection, Patent Document described above discloses a technique of reducing an increase in the circulating resistance described above, however, as long as the end portion itself is existing, it is difficult to completely eliminate the generation of the circulating resistance.
According to the above method of manufacturing a linear guide device, under the condition that the positions of the end portions 59 of all the rolling element rows 62 are aligned, the slider 16 is assembled to the guide rail 12. Due to the foregoing, for example, as shown in FIG. 32(f), in a linear guide device having a plurality of rows of the infinite circulating passages, in the case where the number of the rolling elements composing the rolling element row in the infinite circulating passage and the length of the rolling element accommodating belt are the same as those of the rolling element row in the other infinite circulating passage, the phases of the end portions of the rolling element rows coincide with each other in the aligning direction of the infinite circulating passages. Accordingly, a case, in which the end portion of the rolling element accommodating belt and each portion of the infinite circulating passage interfere with each other, substantially simultaneously occurs with respect to all the infinite circulating passages. Accordingly, vibration and noise are more increased at the time of operation.
In this connection, for example, Patent Document 7 discloses a technique in which end portions of the rolling element accommodating belts, which are opposed to each other, are connected with each other. However, even when the end portions are connected with each other, it is inevitable that the thus connected portion is formed into a special shape with respect to the shape of the other portion. Therefore, even in the case where the end portions are connected to each other, a circulating resistance is generated in the connected end portion which is different from the circulating resistance generated in the other portions. Therefore, when the phases of the infinite circulating passages coincide with each other in the aligning direction, a smooth operation of the linear guide device is obstructed.
According to the technique described in Patent Document 4, the rolling element accommodating section of the rolling element accommodating belt is composed in such a manner that the rolling element accommodating section allows the accommodated rolling element to come off. Therefore, when the rolling element row of this type rolling element accommodating belt is incorporated into the infinite circulating passage, under the condition that one of the lid members is removed from the slider, while the rolling element accommodating belt is intermittently fed into the infinite circulating passage according to the pitch of the rolling element accommodating sections, the rolling elements are accommodated in the rolling element accommodating section from the thus opened portion. In this way, the rolling element row is composed and inserted. After the rolling element row has been inserted into the infinite circulating passage, the lid member, which was removed before, is attached to the slider body. However, even in this technique described in Patent Document 4, positions of the end portions of all the rolling element rows are aligned. From this viewpoint, this technique described in Patent Document 4 is the same as the technique described in Patent Document 2. That is, the phases of the infinite circulating passages coincide with each other in the rolling element aligning direction. Therefore, the problem caused by vibration and noise, which are generated at the time of operation, can not be solved.